Singlet oxygen mediated the selective removal of oxytetracycline in C/Fe₃C/Fe⁰ system as compared to chloramphenicol

Reactive oxygen species (ROS) production for Fe⁰ is limited because of the formed iron corrosion products. In this study, C/Fe₃C/Fe⁰ composite which produces enhanced ROS has been specifically designed and fabricated to remove typical antibiotics (i.e., oxytetracycline (OTC) and chloramphenicol (CAP)) as a heterogeneous Fenton-like catalyst. The C/Fe₃C/Fe⁰ composite demonstrated excellent performance for both OTC and CAP removal as compared with Fe⁰ and biochar. Furthermore, X-ray photoelectron spectrometry, Fourier transform infrared spectrometry, high performance liquid chromatography-mass spectra and electron spin resonance analyses were conducted to elucidate the adsorption and degradation mechanisms. The adsorption of OTC and CAP was mainly dominated by H bonds and the electron-acceptor-acceptor on the surface of the C/Fe₃C/Fe⁰ composite, respectively. In particular, OH simultaneously induced the degradation of OTC and CAP, while ¹O₂ presented the selective oxidation to OTC. More specifically, the degradation of OTC over C/Fe₃C/Fe⁰ was stronger and faster than that of CAP, leading to 65.84% and 16.84% of removal efficiency for OTC and CAP, respectively. Furthermore, C/Fe₃C/Fe⁰ exhibited superior reusability and stability after regeneration, but regenerated Fe⁰ almost lost its reactivity. Therefore, the efficiency in situ generation of ¹O₂ using C/Fe₃C/Fe⁰ would shed new light on the selective oxidation of aqueous organic compounds.